Browsing by Subject "jätevesi"
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(2018)PURPOSE AND GOALS Microalgae are unicellular eukaryotic organisms capable of photosynthesis. They harvest sunlight and efficiently take up carbon dioxide and nutrients such as nitrogen and phosphorus from their environment and use them for their growth. Due to these properties, their rapid growth and ability to survive in a variety of environments, microalgae have potential in biotechnological applications that promote nutrient recovery and recycling, water purification and the carbon neutral production of biochemicals and possibly biofuels. The purpose of this study was to investigate the suitability of a side stream water originating from the production of baker’s yeast (yeastwater) for the cultivation of a species of microalga called Euglena gracilis. The study aimed to determine the capacity of this water to support growth and protein production of E. gracilis as well as the capacity of E. gracilis to remove nutrients from the water. The effect of filtration of the water on these parameters was also studied. Yeastwater contains an organic molecule called betaine in relatively high concentrations. Betaine has previously been shown to boost the production of the important vitamin cobalamin in bacteria. The study aimed to determine the effect of betaine on the growth of E. gracilis and on the production of cobalamin in the algal-bacterial symbiosis. METHODS E. gracilis was cultured in laboratory scale photobioreactors. Its growth, protein production and nutrient uptake capacity was determined. Baker’s yeast production side stream water diluted with MQ-water was used as the growth medium either in filtered or unfiltered form. A control treatment was prepared where no microalgal inoculate was added to the photobioreactor. The same microalga was also grown in a synthetic nutrient medium with and without betaine. The uptake of betaine and biomass concentrations of cobalamin were determined. For the determination of microalgal growth, dry weight determination and flow cytometry analysis were used. Protein production was determined on the basis of total nitrogen concentration in the biomass. Spectrophotometric measuring kits were used for the determination of nutrient concentrations. Liquid chromatography techniques were used for the determination of betaine and cobalamin concentrations. RESULTS Significant microalgal growth was observed in filtered yeastwater, while growth in unfiltered yeastwater was very low. Nitrogen removal was higher in presence of E. gracilis compared to the control treatment. Protein production in yeastwater was comparable to that of microalgae grown in synthetic medium. E. gracilis grew much better in the synthetic media supplemented with betaine than without the addition. Betaine enrichment had no effect on cobalamin production. Cobalamin was produced in unfiltered yeastwater both with and without the presence of E. gracilis. CONCLUSIONS Unfiltered yeastwater does not support growth of E. gracilis possibly due to its high turbidity. Filtered yeastwater, on the other hand can support the production of E. gracilis biomass. E. gracilis can be used to reduce nitrogen concentrations in yeastwater. Yeastwater can support cobalamin production by bacteria, but this phenomenon did not benefit from the presence of the microalga. The effect of betaine on microalgal growth warrants further study to determine whether it is related to the accumulation of intracellular nutrients, storage compounds or to some other phenomenon. Yeastwater is a promising nutrient feedstock for microalgal biomass production. However, the role of filtration and possibility of using other methods for turbidity reduction needs to be further studied.
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(2021)Tutkielman tarkoitus oli selvittää kolmen eri valointensiteetin vaikutuksia mikrolevälajien, E.gracilis ja Selenastrum sp., kasvuun ja karotenoidituotantoon. Käytetyt valointensiteetit olivat 0 (pimeä), 200 ja 400 µmol m-2s-1. Levät kasvatettiin kiertovesikalankasvattamon jätevedessä, minkä vuoksi työssä tarkasteltiin myös ravinnepoistumaa. Kasvatukset havaittiin typpirajoitteisiksi, mikä osaltaan heikensi levien kasvua ja siten karotenoidituotantoa. Jätevesi kasvualustana aiheutti E.gracilis -levän kasvatuksiin kontaminaation vieraslevällä. Karotenoidit eristettiin kasvatuskokeen päätyttyä uuttamalla paineistetulla nesteuutolla (Accelerated Solvent Extraction, ASE) etanolin ja 2-metyylitetrahydrofuraanin liuotinyhdistelmällä. Karotenoidien jatkoanalyysiin käytettiin erittäin korkean erotuskyvyn nestekromatografiaa (UHPLC, Ultra-High Performance Liquid Chromatography) yhdistettynä sähkösumutusionisaatioon ja massaspektrometriin. Tunnistettujen karotenoidien määriä analysoitiin niiden signaalivahvuuksiin ja käytettävissä olleisiin malliaineisiin perustuen. Valointensiteeteillä havaittiin olevan vaikutus levien kasvuun, kokonaiskarotenoidi- ja klorofyllipitoisuuksiin sekä astaksantiiniin, luteiiniin ja neoksantiiniin. Kyseiset erikseen tunnistetut pigmentit olivat kaikki ksantofyllejä, joilla on liialta valointensiteetiltä suojaava tehtävä leväsoluissa. Valointensiteetin sietokyky poikkesi kuitenkin levälajeilla eivätkä sen vaikutukset olleet yksiselitteisiä. Pimeässä levien kasvu ja ravinnepoistuma olivat heikkoja. Pigmenttien säilymisen puolesta pimeä osoittautui jopa voimakkainta valointensiteettiä paremmaksi vaihtoehdoksi. Molempien levien ravinteiden kulutus oli tehokasta. Valointensiteetin lisäksi kasvuun ja karotenoidituotantoon vaikutti muutkin tekijät, kuten kokeen aikana saavutettu kasvuvaihe, jatkuva valotus, kontaminoituminen, ravinnerajoitteisuus sekä käytettyjen malliaineiden laatu. Jatkotutkimuksissa tulisi pyrkiä minimoimaan tai poissulkemaan näiden tekijöiden vaikutukset.
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